Process of treating ores



J. E. GREENA-WALT.

PROCESS OF TREATING ORES. APPLICATION FIL ED NOV-25. 1912.

, Patented Aug. 3 19%.,

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LV' VENTOR. dbizrz E-Greenawa/f.

WITNESSES.-

ATTORNEY. P

J. E. GREENAWA'ILT.

PBOCESS'OF TREATING ORE S. APPLICATION FILED NOV-2'5. 1912 Patented. Aug. 3, 1920.

4 SHEETS-SHEET 2.

WITNESSES: IN VENTOR.

#% a. I I hi? E'G/"enaWa/f' BY WW 6% Q ATTORNEY.

LE. GREENAWALT.

PROCESS OF TREATING CRES- APPLICATION FILED'NOVHZS, 1912;

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UNHTED STATES earner FFHCE.

JOHN E. GREEN'AWALT, 0F DENVER], COLORADO.

PROCESS OF TREATING CRES- Original application filed June 24-, 1912, Serial No. 705,495.

Specification of Letters Patent.

25. 1912. Serial No. 733.475.

To all whom it may concern:

Be it known that 1, JOHN E. GREENA- WALT, citizen of the United States, residing at Denver, in the county of Denver and State of Colorado, have invented certain new and useful Improvements in Process of Treating Ores, of which the following is a full, clear, and exact description, reference being had to the accompanying drawings, forming a part hereof.

My invention has relation to improvements in processes of treating ores (or other material) and it consists in the novel series of steps more fully set forth in the specification and pointed out in the claims.

In the drawings, Figure 1 is a vertical section taken longitudinally through a series of two treatment vessels or pans in which my process is carried out, on the line 1-1 of Fig. 2; Fig. 2 is a vertical section at right angles to Fig. 1 taken on the line 2-2 of Fig. 1; Fig. 3 is a top plan of a pan and one-half of the hood superposed thereover; Fig. 4c is a half side elevation and half middle vertical longitudinal section of a pan and hood superposed thereover and lowered into position thereon; Fig. 5 is a side elevation of the hood and upper edge of a pan, the hood being shown lifted off the pan; Fig. 6 is a half end view and half cross-section of a hood enlarged; and Fig. 7 is. an enlarged sectional detail of a hood on the line 77 of Fig. 3.

The present is a division of my pending application for improvements in sintering apparatus, filed June 24., 1912, Serial Number 7 05,495, being specifically directed to the process involved in the treatment of the charge. The apparatus covered by said pending application though eminently adapted to fulfil the various conditions required by the process, is not the only construction in connection with which the proccan arise which may call for material changes in, or modifications of the apparatus as now built. As clearly obvious from the pending application aforesaid, the primary object of the present invention is to treat or sinter a single charge of ore in such a way as to cause not only a simultaneous ignition of the entire surface of the charge treated, but to cause the propagation of the zone of combustion uniformly and evenly through the charge, it being understood that the down-draft method of supplying air to the charge is here employed, an example of which is shown and described in U. S. Letters Patent 839,064; and 839,065, issued to me under date of December 18, 1906. Under my improved process a maximum single charge may be treated or sintered with the least expenditure .of time and fuel, the process being in no wise limited in its application to any particular composition of the charge. As an example of a charge capable of treatment by my process may be cited flue-dust from pig-iron blast furnaces, and fine iron ores. The flue dust contains from eight to twenty-five percent. of carbon and can be successfully agglomerated by my process, the carbon supplying the necessary fuel for the heat of agglomeration. It is desirable of course, to stop the operation as soon as the sintering or agglomerating of the charge is accomplished so as to retain as much carbon as possible for the subsequent smelting of the charge in a blast furnace. To ores containing neither carbon or sulfur about eight per cent. of fine coal or coke must be added to supply the carbon. A mixture of blast furnace flue dust and ores containing no combustible ingredients gives excellent practical results, the flue dust in some cases containing suiiicient carbon to agglomerate or a down-draft, the air and gases being drawn ess may be practised; and special conditions? tion. Among the objects sought is to pro vide suitable means for distributing the ignition fuel (be it gas, oil or powdered carbonaceous fuel) over the entire surface. of the charge in planes parallel and in proxcurrents which would tend to flow over the surface of the charge and prevent the flames from contacting therewith, the roof of said hood being brought in proximity to the surface of the charge so as to cause the ignition flames to instantly fill the low chamber thus formed and hold the flame against the charge and thereby insure the simultaneous ignition thereof over its entire surface, a

result primarily sought by the present invention. A further object is to cause the ignition fuel to be fully ignited before responding to the draft of the exhauster whereby no unconsumed ignition fuel will enterthe charge. A further object is to introduce the air which supports the combustion of the ignition fuel in properly distributed volumes over the charge so that every molecule of the fuel introduced into the chamber shall be ignited at one time and receive its proper complement of oxygen. To enable those skilled in the art to advantageously practice the invention, I will now describe in detail one form of apparatus eminently adapted to fulfil the various conditions imposed by the process.

Referring to the drawings, 1 represents a pan or receptacle which in practice may be of any convenient size, the dimensions of that here shown being about twelve feet in length, sevenfeet wide and two feet deep, the side walls of the pan being provided with parallel ribs a, b, spaced a suitable distance apart to form a way or groove 0 for the reception of the ends of the grates G, the upper rib a being about ten inches below the edge of the pan, thus permitting the charging of the pan with a layer of ore or other material of substantially twelve inches in thickness. Preferably, the pan is composed of two sections bolted together' through the bottom transverse flanges 2 as shown, the outer ends of the sections terminating, below the grates G and the charge supported thereon, in hollow trunnions 3, 3, which thus communicate with the chamber 4: between the grates and the bottom of the pan, the trunnions being supported on wheel or roller bearings w as shbwn. The trunnions, of each pan (there maybe any number of pans to a plant) communicate with a box or casing 5 from which lead pipes 6, 6, to a suitable fan or exhauster F, the latter being driven by an electric or equivalent motor M. When the exhauster-is in operation, the air and gases are drawn evenly through the charge and its supporting grates, into the chamber 4 and out through the hollow trunnions 3, boxes 5, pipes 6, into and out of the exhauster. The pan is freely rotatable about the common axis of the trunnions 3, (being the longitudinal axis of the pan) and when the charge thereon has been sintered the pan is rotated (by hand or otherwise) about said axissufiicientlv to dump the charge onto a chute or incline 7 whence it is discharged into a car T.

Disposed adjacent the sides of the pan (or pans) 1 are rails R for the support of the wheels 8 mounted to freely rotate on roller bearings 9 at the ends of the stationary axles 10 from which the igniting hood H is suspended. The hood is so supported that it may be raised or lowered from and to the pan with very little effort, the preferred manner of support bein by means of the U-shaped balance levers L, extending in opposite directions across the axles and across the length of the hood, and projecting a suitable distance beyond the ends of the hood, the free ends of the long arms of -the levers being provided with piping or sleeves 11 to be grasped-by the hands of the operator. The sides of the lever frames are fulcrumed to the axle, being preferably riveted to a block 12 secured (if necessary) to the axle, the short arms of the levers (or lever frames) being coupled to the hood by links 13. The weight of the levers approximately balances the weight of the hood, and an oscillation of the levers about the axes of the axles (in which oscillation the axle freely turns in its bearings in the wheels 8) produces a corresponding vertical reciprocation in the hood. When the levers L are horizontal the hood is raised an inch or so (Fig. 5) above the plane of the upper edge of the pan (assuming of course that the pan has been rotated to a horizontal position), so that a slight oscillation of the long arms of the levers L upwardly will depress the short arms and thus lower the hood so thatthe same may rest on the pan, the hood being previously wheeled directly over the pan. The engaging surfaces between the hood and pan are carefully machined so that when the hood rests on the pan a tight joint or seal is formed against the influx of atmospheric cross-currents, the absence of such currents permitting the ignition flame within the igniting chamber of the hood to remain in undisturbed contact with the surface of the charge. The crown of the hood is only about six inches above the surface of the charge, and when we consider that the area of this surface is substantially eighty-four square feet, the ignition cham ber C (above the charge) is comparatively very shallow or low (Figs. 1, 2) thereby keeping the flames within it in close and permanent contact with the surface of the charge. The shallowness of the ignition chamber is an important feature in the present invention as the flame of ignition readily and instantly fills the entire chamber the moment the fuel of ignition is projected into the chamber. The fuel for igniting the charge may be gas or liquid (or even powdered carbon) and is introduced into the chamber C through the sides of the hood, through nozzles 14 leading from pipes 15 traveling with the hood, the intake, ends of the pipes being coupled to flexible hose 16 leading from the main fuel supply pipe 17 and guided over sheaves h and of sufficient length to allow for the necessary travel of the hood over the track or railsR, R. The fuel is fed under a suflicient head to cause its projection into the ignition chamber C across the surface of the charge m in planes parallel and in proximity to said surface, and with sufficient momentum to overcome the suction action of the exhauster so that the fuel becomes fully scattered over the surface of the charge before it can be defiected to any material extent by the currents traversing the charge under the action of the exhauster. The roof of the hood (through which the air supporting combustion of the ignition fuel is admitted) is preferably constructed as shown, that is to say with a series of transverse if-bars 18 to the flanges of which is secured the outer sheet 19 having comparatively large openings or perforations 0 (one and one-quarter inch diameter). Spaced from the sheet 19 is the inner cast iron lining 20 preferably built of sections having comparatively small perforations 0 (one-half inch diameter), the connection being efiected by means of bolts 21 and spacing thimbles 22 whereby an air jacket 23 is formed between the outer sheet and its lining, said jacket keeping the roof of the hood comparatively cool. The vertical walls of the hood are formed preferably of Z-bars t as shown, thecorners of the hood being provided with brackets 24 with central depressions so as to pass around the lower halves of the axles 10 when the .hood is raised to its highest position to clear the pan (Fig. 5).

Traveling over the pan (or series of pans) is a trolley charging car 25 which charges the pans when necessary, this feature not being here entered into in detail as the car forms subject-matter .for a separate application. It is merely illustrated here to show its application to the pans. Features of construction here illustrated but not alluded to are well understood by thepractical engi neer and by those skilled in the art, and require no detailed description in the present connection.

The operation of thejnvention will now be readily understood. A pan having been charged from the car 25 and carefully leveled off (the manner of filling the car not being here entered into because well understood in thevart), the hood is pushed over the pan and then lowered into operative position therewith as already described, an air tight joint being formed between the machined engaging surfaces. As the hood is brought into position the exhauster is started and the operator inserts a lighted torch or flame into the chamber C through a torch hole 26 (normally covered by a swinging plate 27) and opens the valve V (Fig.1) of the main fuel-supply pipe 17 whereupon the fuel is projected across the charge and in planes substantially parallel to the surface thereof, the charge reaching as already stated to the upper edge of the pan and forming in effect the bottom of the ignition chamber C. The momentum of the fuel streams projected across the charge through the nozzles 14 prevents any material deflection thereof by the currents drafted through the charge by the exhauster, and hence no fuel is lost by being drawn prematurely into the charge. The gases of combustion, and the roaster gases, and air (percolating through the roof of the hood to supply the oxygen for the fuel and combustible elements of the charge) are however drawn through the charge and the slots of the grates, and into, through and out of the chamber 4 as already described. The low roof of the ignition chamber C not only insures an instantaneous filling of this chamber with flame which forms a blanket over the charge, but holds the flame blanket in 100 close contact with the entire surface of the charge, any disturbance of such contact being impossible owing to the absence of interfering cross air currents, which are effectively cut off by the seal between the hood 105 and pan. It follows therefore that under the action of the exhauster the zone of com- 'bustion after the surface ofthe charge is once ignited, will permeate the entire with the original area of ignition. In practice the hood once deposited over a pan may rest there until moved over another pan, or it may be removed after the charge is once-- well ignited, the exhauster drawing the zone 5 of combustion through the charge after the removal of the hood. Of course, to remove the hood, the operator simply depresses the levers L which raises-the hood sufiiciently to clear the pan, after which the hood may be 0 readily wheeled out of the way or over the next pan of the series. The charge being fully treated, the operator stops the exhauster, turns the pan on its axis through an angle of approximately one hundred and 1 eighty degrees and dumps the sintered mass onto the chute 7 whence it is received by the car T. Obviously, the fuel supply is cut off by closing the'valve V the moment the having sufficient combustible elements to supply the heat of incipient fusion, in which cases the hood may be removed after ignition of the charge. In treating ores hav ing no appreciable quantities of combustibles, the hood is allowed to remain and the fuel supplied through the nozzles 14 to furnish the necessary heat and air for purposes of oxidation. In the latter cases, of course, the ultimate object of the treatment need not necessarily be to secure a sintering or agglomerating effect, but to recover values.

In order to prevent the fine material m of the charge from clogging and destroying the grates, a layer of coarse porous material m reasonably free from combustible matter, and from one-quarter to one inch in thickness is first deposited on the grates, said coarse and comparatively incombustible layer not only preventing the fine top layer from being drawn through the slots of the grates, but being itself susceptible of ready removal from the grates. This coarse layer too permits an even flow of gases through all portions of the grate surface thereby producing a uniform product. The coarse inert layer forms in effect a porous hearth on which the main charge to be sintered is treated. The charge as a whole is of course, properly mixed and moistened before being deposited on the grate as well understood in the art.

Obviously, the invention need not be restricted specifically to the sintering of ores. In treating sulfid ores for example where the object sought is to remove a maximum amount of sulfur, it is desirable to pass the air and gases through the charge just as long as any sulfur continues to burn; or where the sulfid ore is treated for matte making the gases are drawn,through the charge until just enough sulfur remains in the charge to make it available for this specific purpose, unless the fineness of the charge requires the process to be continued to the point of sintering. In treating iron ores for the blast furnace which do not contain sulfur in injurious quantities, it is desirable to stop the action as soon as the sintering result has been attained, for by this method of procedure considerable carbon can be retained in the sintered material which becomes available in the subsequent blast furnace reduction process. These matters are here mentioned to make it clear that the invention herein is applicable to the treatment or roasting of any ore or material, be the process carried to the point of sintering or incipient fusion or not.

The apparatus herein belongs to what is known as the intermittent type, and one in which the surface of the charge during ignition is never exposed but always covered by an igniting hood forming an ignition chamber above the surface of the charge to be sintered or treated, the igniting flame being turned off as soon as each charge is thoroughly ignited. In the continuous type of apparatus in which the igniting flame burns Y constantly, the portion of the charge which has been ignited is separated from the flame by moving the charge away from the flame. WVhile a somewhat similar separation between the charge and i iter in the intermittent type might be e ected by moving the igniting hood with its flame, away from the ignited charge, the more practical and sensible way of course is to first put out the flame and then remove the hood, if desired, or where it is necessary to move the hood over another pan to ignite another charge. In the present apparatus the gases traverse the charge across the shortest dimension of the mass treated, but obviously I do not wish to be limited in this regard, as in some forms of apparatus the thickness or vertical dimension of the charge may be equal to or exceed the dimensions determining the area of the charge.

Having described my invention, what I claim is 1. In the treatment of ore or other material, the process which consists in subjecting a charge of the material to the traverse of gases through the charge downward from a chamber superposed above the charge, projecting from fixed points above the charge ignition fuel into said chamber, igniting said fuel, and supplying combusting-supporting gasesto the fuel durin the period of its projection into the cham er.

2. In the sintering of ores, the process which consists in subjecting a charge of the ore to the action of an exhauster drafting the gases downwardly through the charge, temporarily maintaining a low i ition chamber above the charge and pro ecting thereinto in proximity and parallel to, the surface of the charge ignition fuel under a sufficient head to overcome any material deflection by the gases drafted through the charge, and supplying air to said fuel whereby the chamber fills with flame and the latter is held against the surface of the char e.

3. n the treatment of ores or. other material containing a combustible component, the process which consists in subjecting a charge of the material to the traverse of gases through the charge from top downward, projecting over the surface of the charge in planes parallel and in proximity thereto, ignition fuel under a head suflicient to prevent material deflection thereof by the currents traversing the charge," igniting said projected fuel, and forming thereof a flaming blanket coextensive with the surface of the charge, maintaining said blanket in contact with the charge and thereby igniting the latter simultaneously over its entire surface, and feeding air to the current traversing the charge whereby oxygen is supplied to the blanket and to the charge.

4. In the treatment of ores or other material, the process which consists in subjecting a charge of the material to the action of a down-draft current of airpermeating and escaping through the charge, projecting above and in planes parallel and in proximity to the upper surface of the charge, streams of ignition fuel under a sufficient head not to be materially deflected by the air current aforesaid, igniting said ignition fuel whereby a sheet of flaming particles blankets the entire surface of the charge, and continuing the down-draft to bring the flaming sheet in intimate contact with the charge and to cause the gases of combustion to be drafted through the charge and heat the latter.

5. In the treatment of ores or other material having a combustible component, the process which consists in subjecting a charge of the material to the action of a downdraft current of air permeating and escaping through the charge, projecting above and in planes parallel and in proximity to the upper 'surfaceof the charge, streams of ignition fuel under a suflicient head not to be materially deflected by the air currents, igniting said ignition fuel whereby a sheet of flaming particles blankets the entire surface of the charge, the charge being ignited simultaneously over its entire surface by said blanket, cutting off the supply of ignition fuel, and continuing the draft of the air currents'to cause the zone of combustion to permeate the entire charge.

6. In the treatment of ores or other material containing a combustible component, the process which consists in subjecting a charge of the material to the traverse of gases through the charge from top downward, projecting suitable ignition fuel across the surface of the chargein planes substantially parallel to said surface and under a head sufficient-to overcome any material deflection from said planes by the currents: traversing the charge, and supplying combustion supporting gases to said ignition fuel, thereby simultaneously igniting the entire surface of the charge.

7. In the sintering of ores, the process which consists in subjecting a charge of the material to the traverse of gases through the charge from top downward, temporarily maintaining a low ignition chamber above the charge and projecting thereinto parallel to the surface of the charge, ignition fuel under a sufficient head to overcome any material deflection thereof by the gases traversing the charge, and supplying air to said fuel whereby the'chamber fills with flame,

and the latter is held against the surface of the charge.

8. In the treatment of ores or other material containing a combustible component, the process which consists in subjecting a charge of the material to the traverse of gases through the charge from top downward, projecting over the surface of the charge in planes parallel and in proximity thereto, ignition fuel under a head sufiicient to prevent material deflection thereof by the currents traversing the charge, igniting said projected fuel, and forming thereof a flaming blanket coextensive with the surface of the charge, maintaining said blanket in undisturbed contact with the charge whereby the latter becomes ignited simultaneously over its entire surface, and feeding a supporter of combustion to the current traversing the charge whereby said supporter is supplied to the blanket and tothe charge.

9. In the treatment of ores or other material, the process which consists in subjecting a charge of the material to the action of a down-draft current of air permeating and escaping through the charge, projecting above and in planes parallel and in proximity to the upper surface of the charge, streams of ignition fuel under a suflicient head not to be materially deflected by the air current aforesaid, igniting said ignition fuel whereby a sheet of flaming particles blankets the entire surface of the charge, and continuing the downdraft and excluding cross-currents to bring the flaming sheet in intimate and undisturbed contact with the charge and-cause the gases of combus tion to be drafted through the charge.

10. In the treatment of ores, or other material, having a combustible component, the process which consists in subjecting a charge of the material. to the action of down-draft currents of air permeating and escaping through the charge, projecting above and in planes parallel and in proximity to'the upper surface of the charge, streams of ignition fuel under a sufficient head not to be materially deflected by the air currents, igniting said ignition fuel whereby a sheet of flaming particles blankets the entire surface of the charge, the charge being ignited simultaneously over its entire surface by said blanket, excluding cross-air currents from said blanket thereby permitting the latter to remain in undisturbed contact with the charge for a predetermined period, cutting off the supply of ignition fuel, and continuing the downdraft of the air-currents to cause the zone of combustion to permeate the entire charge.

11. In the treatment of ores or other material containing a combustible component, the process which consists in subjecting a charge of the material to the traverse of gases through the charge from top downward, delivering from fixed points above the paths substantially parallel to said surface,

and supplying a supporter of combustion to said fuel within the chamber whereby the chamber fills with flame and the latter is held against the-surface of the charge.

13. In the treatment of ore or other material containing a combustible component, the process which consists in subjecting a charge of the material to the traverse of gases through the charge downward from a chamber above the charge, projecting from fixed points above the charge ignition fuel into said chamber, igniting said fuel, supplying combustion-supporting gases to the fuel during the period of its projection into the chamber, and finally cutting off the ignition fuel and continuing the downward traverse of the gases through the charge.

14. In the sintering of ores, the process which consists in subjecting a charge of the ore to the action of an exhauster drafting the gases downwardly through the charge, temporarily maintaining a low ignition chamber above the charge and projecting thereinto in proximity and parallel to, the surface of the charge, ignition fuel under a suflicient head to prevent material deflection thereof by the gases drafted through the charge, maintaining a proper distribution of the ignition fuel over the surface of they charge while projecting the same across said surface, and supplyin air to said fuel whereby the chamber hlls with a flame of even intensity throughout and the flame is held a ainst the surface of the charge.

15. n the treatment of ores and other material, the process which consists in subject ing a charge of the material to the action of an exhauster drafting the gases downwardly through the charge, projecting suitable ignition fuel across the surface of the charge in planes substantially parallel to said surface-and under a head sufiicient to prevent any material deflection thereof from said planes by the currents drafted through the char e, maintaining a proper distribution of the lgnit-ion fuel over the surface of the charge during the projection thereof across said surface, and supplying combustionsupporting gases to said ignition fuel thereby simultaneously igniting the entire surface of the charge.

16. In the treatment of ores or other ma-.

terial, the process which consists in subjecting a charge of the material to the action of a down-draft current of air permeating and escaping through the charge, projecting above and in planes parallel and in proximity to the upper surface of the charge, streams of ignition fuel under a suflicient head not to be materially deflected by the air current aforesaid, maintaining a proper distribution of said fuel over the entire surface of the charge while projecting the same across said surface, igniting said fuel whereby a sheet of flaming. particles of substantially uniform intensity throughout blankets the entire surface of the charge, and continuing the down-draft to bring the flaming sheet in intimate contact with the charge and to cause the gases of combustion to be drafted through the charge and heat the latter.

17. In the treatment of ores'or other material containing a combustible component, the process which consists in subjecting a charge of the material to the traverse of gases through the charge from top downward, projecting suitable ignition fuel across the surface of the charge in planes substantially parallel to said surface and under a head suflicient to prevent any material deflection of the fuel from said planes by the currents traversing the charge, maintaining a proper distribution of the fuel over the entire surface of the charge during the period of projection thereof across the charge, and supplying combustion-supporting gases to said ignition fuel thereby simultaneously igniting the entire surface of the charge.

18. In the treatment of ores and other material, the process which consists in subjecting a charge of the material to the traverse of gases transversely through the charge, temporarily maintaining contiguous to the surface entered by the gases, an ignition chamber sealed against the passage of cross currents, and projecting into said chamber in proximity and parallel to, the

surface of the charge aforesaid, ignition fuel under a sufficient head to overcome material deflection thereof by the gases traversing the charge, and supplying a supporter of combustion to said fuel whereby the chamber fills With flame and the latter is held against the surface of the charge.

19. In the treatment of ores and other material, the process which consists in subjecting a charge of the material to the traverse of gases downwardly through the charge, temporarily maintaining above the charge an ignition chamber sealed against the passage of cross-currents, and projecting into said chamber in proximity and parallel to, the surface of the charge, ignition fuel under a sufficient head to overcome material deflection thereof by the gases traversing the charge, and supplying air to said fuel through the walls of the chamber whereby the chamber fills with flame, and the latter is held against the surface of the charge.

20. In the treatment of ores and other material containing a combustible component, the process which consists in subjecting a charge of the material to the traverse of gasses through the charge from top downward, temporarily maintaining above the charge, an ignition chamber sealed against the flow'of cross-currents, projecting suitable ignition fuel into said chamber in paths substantially parallel and in proximity to, the surface of the charge, and under a head sufficient to prevent any material deflection of the fuel from said paths by the currents traversing the charge, maintaining a proper distribution of the fuel so projected, over the entire surface of the charge, and supplying combustion supporting gases to said ignition fuel thereby simultaneously igniting the entire surface of the charge.

21. The herein described method for the treatment of a mass containing a metal-bearing ore and a "combustible capable of sustaining internal combustion of the mass for the sintering of the ore-bearing material, it consisting in arranging the said mass in a relatively thin stratum permeable to gases passing on the lines of the shortest dimension of the mass, confining the stratum gastight around its edges, inclosing the space immediately above the top surface of the stratum by a chamber gas tight with reference to the said stratum and its support or holder, causing a surface ignition of the stratum at oints within the chamber, supplying com ustion-supportin'g gas to the igniting materials within the said chamber and to the burning particles at the surface of the stratum, causing the passage of combustion-supporting gas through the stratum of material after surface ignition has taken place and continuing such passage until the ore material has been sintered from top to bottom and then removing the stratum of sintered material from the confining means, by tilting the holder.

22. The herein described method for the treatment of a mass of material containing a metal-bearing ore and also a combustible capable of sustaining internal combustion within the mass for the sintering of the orebearing material, it consisting in arranging the said mass in a relatively thin stratum permeable to gases, inclosing the space immediately above the said stratum by a chamber substantially gas-tight with reference to the said stratum and its holder, igniting the combustiblematerial of the said mass at the surface thereof and within the said chamber, separating the stratum'from the igniting means, supplying the combustion-supporting gas to the said chamber and causing it to pass through the said stratum until the ore material has been sintered from top to bottom, and removing the sintered stratum from its holder.

23. The herein described method for the treatment of a mass of material containing a metal-bearing ore and also a combustible capable of sustaining internal combustion within the mass for'the sintering of the orebearing material, it consisting in arranging the said mass in a relatively thin stratum confined gas-tight at its edges but transversely permeable to the passage of gaseous fluids, inclosing the space immediately above the said stratum by a chamber substantially gas-tight with reference to the said stratum and its holder, igniting the combustible material of the said mass at the surface thereof and within the said chamber, causing combustion-supporting gas to pass transversely through the stratum to maintain internal combustion therein until the mass is sintered from top to bottom, removing the sintered mass from its holder, and, between the time of igniting the surface of the stratum and the removal of the sintered mass, causing a separation between such mass and its holder and the aforesaid inclosing chamber.

24. In the treatment of ore or other material containing a combustible component, the process which consists in subjecting a charge of the material to the traverse of gases through the charge downward from a chamber above thecharge, projecting'from fixed points above the charge ignition fuel int said chamber in paths substantially parallel to the surface of the charge and under a head sufficient to overcome any material deflection from said paths by the currents traversing the charge, and supplying compusition-supporting gases to said ignition 25. In the treatment of ore or other material containing a combustible component, thecprocess which consists in subjecting a charge of the material to the traverse of gases through the charge downward from a chamber above the charge, projecting from fixed points above the charge ignition fuel into said chamber in paths substantially parallel to the surface of the charge and under a head suflicient to overcome any material deflection from said paths by the currents traversing the charge, and causing a supporter of combustion to flow into the chamber to sustain combustion of the ignition fuel.

26. The herein described process of treating a mass of metal-bearing ore, with which is commingled a combustible substance, to

cause it to be sintered, which consists in forming a thin pervious layer of the said mass, applying to the upper surface thereof a body of hot igniting gaseous materials over an area commensurate with said surface, drawing said hot gaseous materials into intimate contact with the ore by air currents caused to pass through the body of the ore to insure a good surface ignition, discontinuing the application of the hot igniting gaseous materials, and continuing combustion of the ore mass by the air currents passing through the body of ore to complete the sintering throughout the entire mass.

27. The herein described process of treating a mass of metal-bearing ore, with which is commingled a combustible substance, which consists in forming a thin pervious layer of the said mass upon a perforated support therefor, applying to the upper sur-- face of said layer a body of hot igniting materials over an area commensurate with said surface to insure a good surface ignition, discontinuing the application of the hot igniting materials, and continuing the sintering by internal combustion by the air currents induced to pass through the said mass to cause complete-sintering of the ore from surface to surface, and finally loosening and removing the sintered ore from its support.

In testimony whereof I afiix my signature, in presence of two witnesses.

- JOHN E. GREENAWALT. lVitnesses MARY C. DINNEEN, AUGUSTA DUL. 

